Question

I just begin to maintain a Java MVC project which use Java Guice Framework.

In almost the entire code, first developers passed as parameter an empty model interface extending another interface.

Here’s the first Interface:

public interface FooModel extends ModelInterface {

}

And the other interface:

 public interface ModelInterface {
        public void addListener(FooListener fooListener);
        void setFoo(boolean blop);
        boolean isFoo();
    }

That does not make any sense for me.

Is there a good reason/pattern use empty interface, in Java? Maybe for Guice?

Answer 1

Here is a good motivation for “marker interfaces”. They are especially useful in aspect-oriented programming where they give you a point to attach to (and I guess Guice is just such a framework).